Method of Discovering Services Provided by a Network Repository Function

ABSTRACT

A method of discovering services provided by a network function, NF, in a Service Based Architecture, SBA, based telecommunication network, wherein said network function is registered, in a Network Repository Function, NRF, comprised by said telecommunication network, using a service name, a service address and a selection rule, wherein said selection rule defines a further service address and a precondition for applying said selection rule, said method comprising the steps of receiving, by said NRF, a discovery request, from a Network Function, NF, consumer, wherein said discovery request comprises said service name, determining, by said NRF, that said selection rule applies by determining that said precondition is met based on said received discovery request and transmitting, by said NRF, to said NF consumer, a discovery response, wherein said discovery response comprises said further service address.

RELATED APPLICATIONS

The present application is a continuation of U.S. Parent applicationSer. No. 17/355,592, which was filed on 23 Jun. 2021, which is acontinuation of U.S. patent application Ser. No. 16/629,591, which wasfiled on Jan. 9, 2020, now U.S. Pat. No. 11,064,325, which is a nationalstage application of PCT/EP2018/071925, which was filed Aug. 13, 2018,and claims benefit of U.S. Provisional Application 62/545,177, which wasfiled Aug. 14, 2017, the disclosures of each of which are incorporatedherein by reference in their entirety.

FIELD OF THE INVENTION

The present disclosure generally relates to the field of Service BasedArchitecture, SBA, based telecommunication networks and, morespecifically, to methods and devices for improving the service discoveryprocess.

BACKGROUND

The Fifth Generation, 5G, telecommunications system is understandardization by the Third Generation Partnership Project, 3GPP. Adisruptive change is already agreed wherein traditional peer-to-peerinterfaces and protocols are modified by a so-called Service BasedArchitecture, SBA, comprising a plurality of Network Functions, NFs,where each NF provides one or multiple services as a producer to one ormultiple consumers, by means of a protocol that is under evaluation in3GPP stage 3.

For each NF, services have been defined. For example, for the User DataManagement, UDM, NF the following services are defined:

-   -   UE Context Management, wherein the basic functionality is to        allow a consumer NF to be registered as the serving NF for a        particular User Equipment, UE.    -   Subscriber Data Management, whose basic functionality is to        allow a consumer NF to access to subscription data for a        particular UE.    -   Authentication, wherein the basic functionality is to allow a        consumer NF to get UE authentication data.

One of the drivers of the SBA is to achieve independent Life CycleManagement, LCM, per service. In other words, each SBA service should beable to at least be developed/updated, upgraded, scaled, deployedindependently from any other SBA service defined.

In fact, the expectation is to be able to divide existing NFs, that arebig “containers” of different functionality, into specific andindependent functionality in a way that SW development could beoptimized while reuse is increased. But as well, SW implementation,set-up and orchestration in a Cloud Environment is optimized.

However, some SBA services defined in the Third Generation PartnershipProject, 3GPP, Fifth Generation, 5G, do not follow these principles. Anexample of such a node is the UDM NF whose functionalities have justbeen described. Taking the example of the UDM node, it is further shownhow all NFs have not been optimized for the SBA environment.

The “Subscriber Data Management” service offered by the UDM is mainly aservice to access a Database, DB, that includes DB access operationssuch as query, update, delete, create, subscribe, notify.

The “UE Context Management” service is the service that requires toinclude the most part of the Fourth Generation, 4G, Home SubscriberServer, HSS, logic, e.g. at Registration the consumer requires toreceive some subscription data; the relevant data to be provided,internal authorization and consistency checks, depends on whether theconsumer is Access and Mobility Function, AMF, Session ManagementFunction, SMF, or SMS function, SMSF.

For this reason, the “UE Context Management” service is not well definedto achieve independent LCM, for example:

-   -   Scaling: For AMF, the amount of service requests could be double        than for SMF. Then, in order to be able to apply different        scaling patterns, to optimize internal resources, each different        logic should be defined as a different service, not everything        under the same.    -   Developing/Updating: If some changes may be required for SMSF        business logic, then the whole “UE Context Management” service        will need to be updated. Even though required changes may be        limited to one/some micro-services, it implies that the SW piece        needs updating, re-compilation, basic testing. All development        SW tasks are required for the whole Service. Therefore, it is        advisable to do not mix different functionalities in the same        service, in order to allow independent developing/updating of        each functionality.    -   Upgrading: a SW piece (Service) (or some of its micro-services)        may need upgrading in a real and up and running Cloud Platform.        It is recommended to avoid impacting consumers that are not        really benefited by upgraded functionality. This could be        minimized if each service only provides a specific        functionality. There are techniques like rolling upgrade that        could be used to minimize consumers' service interruption while        upgrading, but the usage could be optimized if each service        clearly provides a limited and specific functionality.        Deployment: it may be required to just deploy e.g. “SMS        Management”, but unless this functionality is defined in an        independent service, independent development will not be        possible. Therefore, UDM services, and other defined services in        3GPP, do not ensure an optimized independent LCM. However,        service definition is already fixed in 3GPP, and implementations        should normally be compliant to that, in a way to ensure        multi-vendor solutions. Therefore, there is a need to redesign        the 3GPP SBA in such a manner to ensure an improved independent        LCM. Reference is made to the 3RD Generation Partnership        Project; Technical Specification group Services and System        Aspects; Procedures for the 5G System; Stage 2 (Release 15)        dates 2 Jun. 2017, XP051298344. Reference is also made to US        2012/203864, which discloses a method and Arrangement in a        Communication Network for Selecting Network Elements.

SUMMARY

It is an object of the present disclosure to overcome the drawback asmentioned above. In a first aspect, there is provided a method ofdiscovering services provided by a network function, NF, in a ServiceBased Architecture, SBA, based telecommunication network, wherein saidnetwork function is registered, in a Network Repository Function, NRF,comprised by said telecommunication network, using a service name, aservice address and a selection rule, wherein said selection ruledefines a further service address and a precondition for applying saidselection rule. The method comprising the steps of:

-   -   receiving, by said NRF, a discovery request, from a Network        Function, NF, consumer, wherein said discovery request comprises        said service name;    -   determining, by said NRF, that said selection rule applies by        determining that said precondition is met based on said received        discovery request;    -   transmitting, by said NRF, to said NF consumer, a discovery        response, wherein said discovery response comprises said further        service address.

The inventors have found a solution which is compliant to already agreedservice definition in 3GPP fifth Generation telecommunication networks.The above will be described in more detail with respect to a UnifiedData Management, UDM, but it is noted that this is just an illustrativeexample. Further, the method as described above ensures an improvedindependent Lifetime Cycle Management per service or sub-service.

In the context of the present disclosure, the term sub-service is usedfor demonstrating that a particular service may be divided in one ofmore sub-services. Each sub-service may provide a slightly differentservice.

The present disclosure is directed to the concept of service discovery.It was found that the presently, already agreed, mechanism for servicediscovery may mainly be kept in place. As such, it is not necessary toamend or change the discovery procedures at present.

It is noted that any Network Function is to make the services itprovides known to a Network Repository Function, NRF, in atelecommunication network. For example a Network Function may provideits services, its service address and its selection rules to the NRF.The NRF may store these data in a database, and may obtain these datafrom the database when required. In one of the aspects of the presentdisclosure, the data may be obtained during a service discovery process.

That is, a particular service consumer, i.e. a Network Function, NF,consumer intends to use a particular service. The NF consumer needs toknow where the particular service can be found. As such, the NF consumersends a discovery request to the NRF for requesting the discovery of aparticular service, i.e. a service name.

The NRF is then, according to the present disclosure, able to determinethat a selection rule applies by determining that a precondition is metbased on the received discovery request. Each service consumer mayindicate that a particular service is provided at a particular serviceaddress, but, in case a pre-condition is met, a discovery request shouldnot be responded with a conventional discovery response, but with anupdated one. That is, is the pre-condition is met, a further serviceaddress is to be provided instead of the more regular service address.

The precondition may be explicitly included in the discovery request, ormay be derived from the discovery request. For example, the entityrequesting the discovery of a particular service may be used as aprecondition, or a particular parameter may be included in the request.

In an example, the precondition relates to any of:

-   -   a particular NF consumer type such as an Access and Mobility        Management function, AMF, or a Session Management Function, SMF;    -   a particular consumer identification.

Thus, in case the discovery request originates from a predefinedparticular NF consumer type, such as an AMF or SMF or the like, theprecondition is considered to be met and the selection rule is to beapplied.

In a further example, the NF is registered in said NRF using a servicename, a service address and a plurality of selection rules, wherein eachselection rule defines a further, distinct, service address and acorresponding precondition for applying said corresponding selectionrule.

The further, distinct, service address may be an Internet Protocol, IP,address, or any other address, for example a Fully Qualified DomainName, FQDN, with which said service may be found within thetelecommunication network. It is further noted that the same IP addressas the “standard” IP address may be used for the further serviceaddress, but then with a different port, or anything alike.

In a further example, the plurality of selection rules are associatedwith a prioritization order for determining which of said plurality ofselection rules apply when multiple preconditions are met.

Pragmatically, it may happen that a particular discovery request isreceived, and that multiple preconditions are met for that particulardiscovery request. The advantage of the above described example is that,in such a case, it is still possible to apply a single selection rule.The prioritization determined which selection rule is to be applied.

In a further example, the method comprises the steps of:

-   -   receiving, by said NRF, from said NF, a service registration        request for registering said NF in said NRF, wherein said        registration request comprises said service name, said service        address and said selection rule;    -   storing, by said NRF, said service name, said service address        and said selection rule;    -   transmitting, by said NRF, to said NF, a service registration        response for acknowledging said received registration request.

The above described example described the situation in which a serviceproduces is able to register its services in the NRF, and is able toregister the preconditions that are to be met for applying a particularselection rule for its services.

In a further example, the service address and said further serviceaddress are any of:

-   -   an Internet Protocol, IP, address;    -   a Fully Qualified Domain Name, FQDN.

In a second aspect, there is provided a method of registering a serviceprovided by a network function, NF, in a Service Based Architecture, SBAbased telecommunication network, in a Network Repository Function, NRF,comprised by said telecommunication network, wherein said methodcomprises the steps of:

-   -   transmitting, by said NF, a service registration request to said        NRF, wherein said service registration request comprises a        service name, a service address and a selection rule, wherein        selection rule defines a further service address and a        precondition for applying said selection rule;    -   receiving, by said NF, from said NRF, a service registration        response thereby indicating that said service is registered at        said NRF.

The above described example described the situation in which aparticular service producer, i.e. NF, is to register its services in anNRF. The existing discovery request is then to be updated in that thediscovery request comprises the service name, a service address and aselection rule, wherein the selection rule defines a further serviceaddress and a precondition for applying said selection rule.

In a third aspect, there is provided a Network Repository Function, NRF,arranged to support in discovering services provided by a networkfunction, NF, in a Service Based Architecture, SBA, basedtelecommunication network, wherein said network function is registered,in said Network Repository Function, NRF, comprised by saidtelecommunication network, using a service name, a service address and aselection rule, wherein said selection rule defines a further serviceaddress and a precondition for applying said selection rule, said NRFcomprising:

-   -   receive equipment arranged for receiving a discovery request,        from a Network Function, NF, consumer, wherein said discovery        request comprises said service name;    -   process equipment arranged for determining that said selection        rule applies by determining that said precondition is met based        on said received discovery request;    -   transmit equipment arranged for transmitting to said NF        consumer, a discovery response, wherein said discovery response        comprises said further service address.

The advantages of the first aspect of the disclosure are also inherentlya part of the second aspect, and third aspect, of the disclosure.Furthermore, it is pointed out that although the claims read as if allthe modules/equipment according to this second aspect of the presentdisclosure are incorporated into a single node, a person skilled in theart understands that the same disclosure could be implemented by, forexample, distributing each of the modules over several nodes.Alternately, the disclosure could also be purely implemented in thecloud, whereby none of the physical nodes possess any of thesemodules/equipment as such.

Further, it is noted that the equipment may also be referred to as amodule, unit, device or anything alike.

In an example, the precondition relates to any of:

-   -   a particular NF consumer type such as an Access and Mobility        Management function, AMF, or a Session Management Function, SMF;    -   a particular consumer identification.

In a further example, the NF is registered in said NRF using a servicename, a service address and a plurality of selection rules, wherein eachselection rule defines a further, distinct, service address and acorresponding precondition for apply said corresponding selection rule.

In another example, the plurality of selection rules are associated witha prioritization order for determining which of said plurality ofselection rules apply when multiple preconditions are met.

In an even further example, the receive equipment is further arrangedfor receiving, from said NF, a service registration request forregistering said NF in said NRF, wherein said registration requestcomprises said service name, said service address and said selectionrule;

-   -   and wherein said NRF comprises store equipment arranged for        storing said service name, said service address and said        selection rule;    -   and wherein said transmit equipment is arranged for transmitting        to said NF, a service registration response for acknowledging        said received registration request.

In another example, the service address and said further service addressare any of:

-   -   an Internet Protocol, IP, address;    -   a Fully Qualified Domain Name, FQDN.

In a fourth aspect of the present disclosure, there is provided anetwork function, NF, arranged for registering a service provided bysaid NF, in a Service Based Architecture, SBA based telecommunicationnetwork, in a Network Repository Function, NRF, comprised by saidtelecommunication network, wherein said NF comprises:

-   -   transmit equipment arranged for transmitting a service        registration request to said NRF, wherein said service        registration request comprises a service name, a service address        and a selection rule, wherein selection rule defines a further        service address and a precondition for applying said selection        rule;    -   receive equipment arranged for receiving from said NRF, a        service registration response thereby indicating that said        service is registered at said NRF.

In a fifth aspect, there is provided a computer program productcontaining computer program code which, when executed by a NF, cause theNF to implement a method in accordance with any of the method examplesas provided above.

The above mentioned and other features and advantages of the disclosurewill be best understood from the following description referring to theattached drawings. In the drawings, like reference numerals denoteidentical parts or parts performing an identical or comparable functionor operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a part of the architecture of a FifthGeneration, 5G, telecommunication network.

FIG. 2 schematically illustrates an exemplary Network Function, NF, of a5G telecommunication network.

FIG. 3 schematically illustrates an exemplary optimisation of an NF of a5G telecommunication network.

FIG. 4 schematically illustrates an exemplary optimisation of an NF of a5G telecommunication network.

FIG. 5 schematically illustrates a method according to the presentdisclosure.

FIG. 6 schematically illustrates a method according to the presentdisclosure.

FIG. 7 schematically illustrates an NF according to the presentdisclosure.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a part of the architecture of a FifthGeneration, 5G, telecommunication network, 1. In FIG. 1 , referencenumeral 1 indicates a reference architecture for a 5G system. The 5Gsystem architecture comprises the following Network Functions, NFs:

-   -   Authentication Server Function, AUSF, 6    -   Access and Mobility Management Function, AMF, 7    -   Data network, DN, e.g. operator services, Internet access or 3rd        party services, 5    -   Network Exposure Function, NEF, 12    -   NF Repository Function, NRF, 11    -   Policy Control Function, PCF, 10    -   Session Management Function, SMF, 8    -   Unified Data Management, UDM, 13    -   User Plane Function, UPF, 4    -   Application Function, AF, 9    -   User Equipment, UE, 2    -   (Radio) Access Network, (R)AN, 3.

The functional description of these network functions is specified inclause 6 of the 3GPP standard 23.501, “System Architecture for the 5Gsystem”. Specifically, in FIG. 1 , reference numeral 1 indicates thesystem architecture for a 5G telecommunication network in a roamingcase. That is, the UE 2 is not in the telecommunication network where itoriginally belongs to, i.e. is registered. The UE 2 is originallyregistered with a home network 16, but is presently located in a visitednetwork 15. Such a representation is shown merely for illustrativepurposes and is not a limitation of the teachings according to thepresent disclosure.

FIG. 2 schematically illustrates an exemplary Network Function, NF, of a5G telecommunication network. Reference numeral 20 relates to asituation wherein a consumer service 21 requests a particular servicefrom a producer service 30. As an example, the producer service 30 couldbe a UE context management service offered by the UDM. Such as serviceis implemented in a cloud environment by means of several micro services41-48. The number of micro services and the function performed by eachmicro service is dependent on the NF and is also dependent on theinternal Software architecture.

The micro services are contained within corresponding Virtual NetworkFunction Containers, VNFCs, 31-38. Again considering the example thatservice 30 refers to a UE context management service offered by the UDM,and the AMF logic requires different micro services than an SMF logic.Such an example is represented by reference numerals 50 and 55 in FIG. 3.

Reference numeral 51 refers to a group of micro services—41, 42, 44, 45,46, and 48 that are required by the AMF logic and another group 52formed by micro services—41, 43, 47 and 48 that are required by the SMFlogic. Ideally, to achieve the best independent Life Cycle Management,LCM, per service, it would have been better to define AMF management andSession Management as two independent services and not as part of the UEcontext management service.

According to the present disclosure it is proposed, once the standard isdefined, to optimize LCM based on optimization criteria for serviceregistration and discovery. For example, in the above mentionedscenario, the optimization criteria could be the consumer NF type, suchthat the AMF logic 51 is executed when the consumer NF is the AMF andsession management logic 52 is executed when the consumer NF is the SMF.

FIG. 4 schematically illustrates an exemplary optimisation of an NF of a5G telecommunication network. Reference numeral 60 indicates anembodiment of an optimized UDM function, wherein two optimized subservices 51, 52 have been defined. One of the two sub-services 51 is forAccess and Mobility management, when the consumer is the AMF 7 and theother 52 is for session management when the consumer is the SMF 8. Inthis example, the UE context management service offered by the UDM hasbeen optimized with an optimisation criteria of the consumer NF type.The skilled person understands that other network functions may also besimilarly optimized based on different optimization criteria.Alternately, a same network function may be optimized in multiple waysusing multiple optimisation criteria.

It is also possible that when independent micro-services are defined,some micro-services may be found in multiple sub-services. In theexemplary embodiment shown in FIG. 4 , micro services 41 and 48 may befound in both the sub services 51 and 52. Micro service 41 may be, forexample, required for implementing the multivendor interfaces such asRepresentational State Transfer, REST. As an example, micro-service 38could be required in both sub-services 51, 52 to implement access to theUDR. But apart from these two micro services 41, 48, the rest of themicro-services could be totally specific for each sub-service.

FIG. 5 schematically illustrates a method 70 according to the presentdisclosure. More specifically, the method 70 shows a modifiedregistration process after considering an optimization process accordingto the present disclosure. As defined in 3GPP 5G TechnicalSpecification, TS, each NF producer 71 registers 72 the services itoffers in the NRF 11. At least the following parameters are included:

-   -   Service name, identifying the service being registered.    -   Service address. The service address could be, for example, an        Internet Protocol, IP, address or a Fully Qualified Domain Name,        FQDN. This may be used by a consumer service to contact the        producer service.

According to at least an embodiment of the present disclosure, it isproposed to add optional optimization criteria, i.e. preconditions andselection rules. It should be defined in a way that new optimizationcriteria could be added. An example optimization criteria is the NFtype.For each criteria, a different Service address is required. This is usedto contact the optimized sub-service.

In the example, NFtype=AMF is used as the criteria to identify the UEContext management service 51 optimized for Access&Mobility management.Multiple values for the same criteria may be provided, like e.g.NFtype=SMF. Or even multiple optimization criteria, in which case, itmay be required to define a prioritization order, in case multiplecriteria may not be valid for the same sub-service.

Definition of optimization criteria and enhancement of the ServiceRegistration may be subject to potential standardization in 3GPP 5G formultivendor solutions. Standardization may be avoided by someconfiguration in NRF 11, such as by providing specific Service Addressesper NFtype.

In a further step 63, the NRF 11 stores provided one or multiple Serviceaddresses. One address for the SBA service is always provided, andoptionally additional addresses could be provided to identify differentsub-services, altogether with the optimization criteria, to allow NRF toidentify when each Service address should be provided. At the end, theNRF 11 sends a service registration response 74 to the NF producer 71.

FIG. 6 schematically illustrates a method 80 according to the presentdisclosure. Specifically, the method 80 illustrates a method for servicediscovery according to the present disclosure. Service discovery may notneed any enhancement as long as the optimization criteria is a valuethat is already provided at regular service discovery. This is the casefor the NF type. A service is stored 81 in the NRF 11 according to themethod 70.

An NF consumer 81 sends a service discovery request 83 to the NRF 11.Any other optimization criteria not included already for regular Servicediscovery would need to be defined as optional parameters, subject tostandardization, as mentioned for service registration 70. In anexample, NF Type will serve as optimization criteria as this parametermay normally be used for service discovery anyway. Other optimizationcriteria could optionally be added to the request. If so, the Servicediscovery service will need to be enhanced, and then subject tostandardization for multivendor solutions, or a proprietary solution forE/// solutions.

If an optimization criteria is matched 84, then the correspondingsub-service address is provided 85 instead of the SBA service address.According to an example, when AMF is the consumer, the address of thesub-service 51 may be provided, instead of AS-Address. If, however, nooptimization criteria is matched 86, then the corresponding SBA serviceaddress is provided 87. In our example, AS-Address.

FIG. 7 schematically illustrates an NF according to the presentdisclosure.

Other variations to the disclosed examples can be understood andeffected by those skilled in the art in practicing the claimeddisclosure, from a study of the drawings, the disclosure and theappended claims. In the claims, the word “comprising” does not excludeother elements or steps and the indefinite article “a” or “an” does notexclude a plurality. A single processor or other unit may fulfil thefunctions of several items recited in the claims. The mere fact thatcertain measures are recited in mutually different dependent claims doesnot indicate that a combination of these measures cannot be used toadvantage.

A computer program may be stored/distributed on a suitable medium, suchas optical storage medium or a solid-state medium supplied together withor as part of other hardware, but may also be distributed in otherforms, such as via the Internet or other wired or wirelesstelecommunication systems. Any reference signs in the claims should notbe construed as limiting scope thereof.

The present disclosure is not limited to the examples as disclosedabove, and can be modified and enhanced by those skilled in the artbeyond the scope of the present disclosure as disclosed in the appendedclaims without having to apply inventive skills.

What is claimed is:
 1. A method of discovering services provided by anetwork function (NF) producer in a Service Based Architecture (SBA)based telecommunication network, wherein the NF producer is registeredin a Network Repository Function (NRF) comprised by thetelecommunication network using a service name, a service address, andat least one selection rule, with each of the at least one selectionrule defining a further, distinct, service address and a preconditionfor applying the selection rule, the method comprising the NRF:receiving a discovery request from a NF consumer, wherein the discoveryrequest comprises one or more discovery parameters; determining aselection rule from the at least one selection rule based on the one ormore discovery parameters; and transmitting a discovery response to theNF consumer, wherein the discovery response comprises, instead of theservice address, the further, distinct, service address associated withthe selection rule determined from the at least one selection rule. 2.The method of claim 1 further comprising determining that the selectionrule applies by determining that the precondition is met based on thereceived discovery request.
 3. The method of claim 1 wherein aprioritization order indicates which of the at least one selection ruleapplies when multiple preconditions are met.
 4. The method of claim 1,wherein the precondition relates to: a particular NF consumer type; or aparticular consumer identification.
 5. The method of claim 1, furthercomprising the NRF: receiving, from the NF producer, a serviceregistration request for registering the NF producer in the NRF; whereinthe registration request comprises the service name, the serviceaddress, and the selection rule; storing the service name, the serviceaddress, and the selection rule; and transmitting, to the NF producer, aservice registration response for acknowledging the receivedregistration request.
 6. The method of claim 1, wherein the serviceaddress and the further, distinct, service address comprise: an InternetProtocol (IP) address; and/or a Fully Qualified Domain Name (FQDN).
 7. ANetwork Repository Function (NRF) configured to support discoveringservices provided by a network function (NF) producer in a Service BasedArchitecture (SBA) based telecommunication network, wherein the NFproducer is registered in the NRF comprised by the telecommunicationnetwork using a service name, a service address, and at least oneselection rule, with each of the at least one selection rule defining afurther, distinct, service address and a precondition for applying theselection rule, the NRF comprising: receive circuitry configured toreceive a discovery request from a Network Function (NF) consumer,wherein the discovery request comprises one or more discoveryparameters; processing circuitry configured to determine aa selectionrule from the at least one selection rule based on the one or morediscovery parameters; and transmit circuitry configured to transmit adiscovery response to the NF consumer, wherein the discovery responsecomprises, instead of the service address, the further, distinct,service address associated with the selection rule determined from theat least one selection rule.
 8. The NRF of claim 7 wherein theprocessing circuitry is further configured to determine that theselection rule applies by determining that the precondition is met basedon the received discovery request.
 9. The NRF of claim 7 wherein aprioritization order indicates which of the at least one selection ruleapplies when multiple preconditions are met.
 10. The NRF of claim 7,wherein the precondition relates to: a particular NF consumer type; or aparticular consumer identification.
 11. The NRF of claim 7: wherein thereceive circuitry is further configured to receive, from the NFproducer, a service registration request for registering the NF producerin the NRF, wherein the registration request comprises the service name,the service address, and the selection rule; wherein the NRF comprisesstorage configured to store the service name, the service address, andthe selection rule; and wherein the transmit circuitry is configured totransmit, to the NF producer, a service registration response foracknowledging the received registration request.
 12. The NRF of claim 7,wherein the service address and the further, distinct, service addressare: an Internet Protocol (IP) address; and/or a Fully Qualified DomainName (FQDN).
 13. A non-transitory computer readable recording mediumstoring a computer program product for discovering services provided bya network function (NF) producer in a Service Based Architecture (SBA)based telecommunication network, wherein the NF producer is registeredin a Network Repository Function (NRF) comprised by thetelecommunication network, using a service name, a service address, andat least one selection rule, wherein the t least one selection ruledefines a further, distinct, service address and a precondition forapplying the at least one selection rule, the computer program productcomprising program instructions which, when executed by processingcircuitry of the NRF, causes the NRF to: receive a discovery requestfrom a Network Function (NF) consumer, wherein the discovery requestcomprises one or more discovery parameters; determine a selection rulefrom the at least one selection rule based on the one or more discoveryparameters; and transmit a discovery response to the NF consumer,wherein the discovery response comprises, instead of the serviceaddress, the further, distinct, service address associated with theselection rule determined from the at least one selection rule.
 14. Thenon-transitory computer readable recording medium of claim 13 whereinthe program instructions, when executed by the processing circuitry ofthe NRF, further causes the NRF to determine that the selection ruleapplies by determining that the precondition is met based on thereceived discovery request.
 15. The non-transitory computer readablerecording medium of claim 13 wherein a prioritization order indicateswhich of the at least one selection rule applies when multiplepreconditions are met.
 16. The non-transitory computer readablerecording medium of claim 13, wherein the precondition relates to: aparticular NF consumer type; or a particular consumer identification.17. The non-transitory computer readable recording medium of claim 13,wherein the program instructions, when executed by the processingcircuitry of the NRF, further causes the NRF to: receive, from the NFproducer, a service registration request for registering the NF producerin the NRF, wherein the registration request comprises the service name,the service address, and the selection rule; store the service name, theservice address, and the selection rule in a storage at the NRF; andtransmit, to the NF producer, a service registration response foracknowledging the received registration request.
 18. The non-transitorycomputer readable recording medium of claim 13, wherein the serviceaddress and the further, distinct, service address are: an InternetProtocol (IP) address; and/or a Fully Qualified Domain Name (FQDN).